<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>3_回调ref中回调执行次数的问题</title>
  </head>
  <body>
    <!-- 准备好一个“容器” -->
    <div id="test"></div>

    <!-- 引入react核心库 -->
    <script type="text/javascript" src="../js/react.development.js"></script>
    <!-- 引入react-dom，用于支持react操作DOM -->
    <script
      type="text/javascript"
      src="../js/react-dom.development.js"
    ></script>
    <!-- 引入babel，用于将jsx转为js -->
    <script type="text/javascript" src="../js/babel.min.js"></script>

    <script type="text/babel">
      //创建组件
      class Demo extends React.Component {
        state = { isHot: false }

        showInfo = () => {
          const { input1 } = this
          alert(input1.value)
        }

        changeWeather = (c) => {
          //获取原来的状态
          const { isHot } = this.state
          //更新状态
          this.setState({ isHot: !isHot })
        }

        saveInput = (c) => {
          this.input1 = c
          console.log('@', c)
        }

        render() {
          const { isHot } = this.state
          return (
            <div>
              <h2>今天天气很{isHot ? '炎热' : '凉爽'}</h2>
              {/*<input ref={(c)=>{this.input1 = c;console.log('@',c);}} type="text"/><br/><br/>,内联函数写法在更新时将会被调用俩次，因为会被清空一次*/}
              <input ref={this.saveInput} type="text" />
              <br />
              <br />
              <button onClick={this.showInfo}>点我提示输入的数据</button>
              <button onClick={this.changeWeather}>点我切换天气</button>
            </div>
          )
        }
      }
      //渲染组件到页面
      ReactDOM.render(<Demo />, document.getElementById('test'))
    </script>
  </body>
</html>
